Association between changes in cortical and jaw motor activities during sleep

In normal sleep, cortical EEG activity is influenced by the balance in the activities of subcortical neurons in relation to the cyclic changes of sleep states. As well, jaw motor excitability is altered under the activity of sleep regulatory mechanism. Transient arousals (e.g., micro-arousal) are associated with a brief change of cortical activity and an increase of jaw motor activity. During this period, various types of jaw motor activities are occasionally found to occur, with either non-specific or specific patterns such as rhythmic activations. Exaggeration of the jaw motor activities during sleep can be seen in patients with sleep bruxism. Although cortical activity reflects arousal level and is correlated with the activity level of jaw muscles during sleep, it remains to be investigated whether or not cortex plays one of the sources of descending excitatory drive shaping a variety of jaw motor activities.